The Networked Society and Internet of Things (loT) are associated with new requirements on cellular networks, e.g. with respect to device cost, battery lifetime and coverage. To drive down device and module cost, using a system-on-a-chip (SoC) solution with integrated power amplifier (PA) is highly desirable. However, it is feasible for the current state-of-the-art PA technology to allow 20-23 dBm transmit power when the PA is integrated to SoC. This constraint limits uplink “coverage”, which is related to how much the path loss is allowed between the user terminal and base station. To maximize the coverage achievable by an integrated PA, it is necessary to reduce PA backoff. PA backoff is needed when the communication signal has non-unity peak-to-average power ratio (PAPR). The higher the PAPR is, the higher PA backoff required. Higher PA backoff also gives rise to lower PA efficiency, and thus lower device battery life time. Thus, for wireless IoT and other technologies, designing an uplink communication signal that has as low PAPR as possible is critically important for achieving the performance objectives concerning device cost, battery lifetime and coverage.
3GPP is standardizing Narrowband IoT (NB-IoT) technologies. There is strong support from the existing LTE eco-system (vendors and operators) for evolving existing LTE specifications to include the desired NB IoT features. LTE uplink however is based on single-carrier frequency-division multiple-access (SC-FDMA) modulation for the uplink data and control channels, and Zadoff-Chu signal for random access. Due at least in part to the PAPR properties of these signals, there remains a need for improvement to uplink access.